Apparatus for and method of manufacturing flexible tubing

ABSTRACT

Flexible tubing is made from a continuous strip of material which has a roughly U-shaped portion along one side edge and a flange along an opposite side edge. A leading end portion of the strip is held against a rotatable support during rotation of the support enabling helical winding of the strip into a plurality of adjacent turns to define flexible tubing. Guide means guide the U-shaped portion so that it envelops the flange to define a seam and die means having stationary forming surfaces engage and change the cross-sectional configuration of the seam to interlock the U-shaped portion and flange together.

United States Patent Carroll [451 July 18, 1972 Primary Examiner-Richard J. Herbst Assistant Examiner-R. M. Rogers Anamey-Reuben Wolk and Strauch, Nolan, Neale, Nies, Kurz ABSTRACT Flexible tubing is made from a continuous strip of material which has a roughly U-shaped portion along one side edge and a flange along an opposite side edge. A leading end portion of the strip is held against a rotatable support during rotation of the support enabling helical winding of the strip into a plurality of adjacent turns to define flexible tubing. Guide means guide the U-shaped portion so that it envelops the flange to define a seam and die means having stationary forming surfaces engage and change the cross-sectional configuration of the seam to interlock the U-shaped portion and flange together.

29 Clains, 16 Drawing Figures PATENTEB JUL 1 8 I972 SHEET 1 0F 4 INVENTOR HAROLD E. CARROLL A TT'OR/VE' Y PATENlEnJuLwmz 3,677,046

sum 3 OF 4 INVENTOR HAROLD E. CARROLL ATTORNEY PATENIEnJuusmn 3571045 SHEET 0F 4 INVENTOR HAROLD E. CARROLL MZ MA A T TOR/V5 Y APPARATUS FOR AND METHOD OF MANUFACTURING FLEXIBLE TUBING BACKGROUND OF THE INVENTION Apparatus and methods have been proposed heretofore for making flexible metal tubing by winding an elongated strip in a helical pattern while simultaneously fastening a side edge of the strip to the formed tubing. However, such previously proposed apparatus and methods require numerous cooperating forming rollers and associated mechanical linkages and drives which are complicated, expensive, and difficult to maintain in satisfactory operating condition over extended periods whereby such apparatus and methods are inadequate.

SUMMARY This invention provides an improved apparatus for and method of making flexible tubing in a simple and economical manner from a continuous strip of material which has a roughly U-shaped portion along one side edge and a flange along its opposite side edge. A leading end portion of the strip is held against a rotatable support during rotation of the support enabling helical winding of the strip into a plurality of adjacent turns to define flexible tubing. Guide means guide the U-shaped portion so that it envelops the flange to define a seam and die means having stationary forming surfaces engage and change the cross-sectional configuration of the seam to interlock the U-shaped portion and flange together.

Other details, uses, and advantages of this invention will be readily apparent from the exemplary embodiment thereof presented in the following specification, claims, and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings show a present exemplary embodiment of this invention, in which FIG. 1 is a perspective view with parts in cross section and parts broken away illustrating flexible tubing made using the apparatus and method of this invention;

FIG. 2 is a perspective view with parts broken away illustrating one exemplary embodiment of the apparatus and method of this invention;

FIG. 3 is an enlarged view taken essentially on the line 33 of FIG. 2;

FIG. 4 is a greatly enlarged view with parts broken away taken essentially on the line 44 of FIG. 3;

FIG. 5 is a fragmentary view with parts in cross section illustrating the first of a plurality of successive forming dies comprising the apparatus of FIG. 2;

FIG. 6 is a view taken on the line 6-6 of FIG. 5;

FIG. 7 is a cross-sectional view illustrating a U-shaped portion extending from a side edge of an elongated strip positioned around a flange extending from the opposite side edge to define a seam which is then passed through the first die of FIG. 5;

FIG. 8 is a view similar to FIG. 7 illustrating a substantially L-shaped configuration defined in the seam by the die of FIG.

FIG. 9 is a view similar to FIG. 5 illustrating the second die of the plurality of successive forming dies;

FIG. 10 is a view taken on the line 10I0 of FIG. 9;

FIG. 11 is a cross-sectional view illustrating the bifolded configuration of the interlocked seam as it leaves the die of FIG. 9;

FIG. 12 illustrates the manner in which roller means comprising the apparatus of FIG. 2 is used to partially flatten the bifolded seam, as it leaves the die of FIG. 9, from the dotted line to the solid line configuration illustrated;

FIG. 13 is a view similar to FIG. 12 illustrating the manner in which a toothed wheel further flattens the interlocked seam from the dotted line to the solid line configuration to thereby further strengthen such seam;

FIG. 14 is a perspective view illustrating a fixture comprising the apparatus of FIG. 1 and having guide means for guiding the elongated strip to the first of the successive forming dies;

FIG. 15 is a view taken on the line 15-15 of FIG. 14; and FIG. 16 is a view taken on the line 16l6 of FIG. 15.

DESCRIPTION OF ILLUSTRATED EMBODIMENT Reference is now made to FIG. 2 of the drawings which illustrates one exemplary embodiment of the apparatus and method of this invention which is designated generally by the reference numeral 20. The apparatus has a convoluting assembly 22 which is adapted to receive a web or elongated strip 23 of material and define integral convolutions across its width as illustrated in FIG. 4 of the drawings. The strip 23 is wound on a supply roll 24 thereof which is supported for unwinding rotation on a shaft 25 carried by a support bracket 26 and, if desired, the supply roll may be provided with suitable tensioning means and a brake device for reasons well known in the art.

The convoluting assembly 22 of this example has a plurality of seven sets of cooperating rollers with each set being designated by the reference numeral 27. The assembly 22 forms the strip 23 to the configuration illustrated in FIG. 4 defined by a central portion 28 having a plurality of substantially identical convolutions, a roughly U-shaped portion 31 extending vertically upwardly in one direction from a side edge 32, and a flange 33 extending vertically upwardly in the same direction as the U-shaped portion 31 from an opposite side edge 34 and the formed or convoluted strip will be designated by the reference numeral 30. The formed strip 30 may be provided with any desired configuration intermediate its U-shaped portion 31 and flange 33 merely by suitably modifying the construction and arrangement of the sets 27 of cooperating rollers comprising the assembly 22.

The apparatus 20 has a rotatable support in the form of a spindle 36 which is driven by a drive motor 37 which may be provided with a suitable gear reducer assembly, or the like;

- and, has means, indicated generally by the reference numeral 40 in FIG. 3, for holding the leading end portion of the convoluted strip 30 against the rotatable spindle 36 during rotation thereof enabling helical winding of the strip into a plurality of adjacent turns 41 to define the flexible tubing 42 which is illustrated in FIGS. 1 and 2. The apparatus 20 has guide means indicated generally at 43 in FIG. 2 for guiding the U-shaped portion 31 so that it envelops, i.e., is positioned around, the flange 33 of the convoluted strip 30 to define what will be referred to as a seam 44, see FIG. 7. The apparatus 20 also has die means having stationary forming surfaces which engage and change the cross-sectional configuration of the seam 44 to interlock the U-shaped portion 31 and the flange 33 together to provide a high strength mechanical junction and in a manner which makes it impossible for the joined components to be pulled apart without practically destroying portions of the tubing defining the junction.

The apparatus and method 20 may be used to make tubing 42 to any desired length because with such tubing being made from the web 23, the trailing end portion of a web from an exhaused supply roll may be easily spliced to the leading end portion of a new supply roll and thereby enable continuous forming. However, it is common practice to cut the tubing 42 to predetermined lengths and for this purpose a cutting device 45 is provided and includes a cutting wheel 46 which is driven by motor 47 and the device 45 is supported on a carriage 50. The carriage 50 is supported for horizontal movement by a table 51 and an actuator 52 may be provided for moving the carriage and device 45 back and forth on the table 51.

The carriage 50 has wheels which support it for movement on table 51 and has a shaft 53 extending laterally outwardly therefrom which rotatably supports a cam roller 54. The cam roller is adapted to engage an inclined cam surface 55 suitably supported on the table 51 which serves to tilt the carriage and hence the cutting wheel 46 partially around the periphery of the tubing 42 to provide efficient cutting without requiring the wheel 46 to extend a substantial distance within such tubing.

The movement of the actuator 52 and hence cutting device 45 may be precisely controlled automatically using any technique known in the art to provide continuous severing during the manufacturing of flexible tubing; however, it will be appreciated that the movement of the carriage 50 and cutting device 45 may be provided manually, if desired.

As previously mentioned, the apparatus 20 has holding means 40 for holding a leading end portion of the strip 30 against the rotatable spindle 36 and in this example such means comprises a pair of toothed wheels each designated by the reference numeral 56. Each wheel 56 is keyed to a shaft 57 which is carried by a slide member 60 comprising a slide assembly 61 which is supported for sliding movement toward and away from the central axis 62 of the spindle 36 in a known manner.

The apparatus 20 has a detachable fixture 63 comprised of a vertical support plate 64 which supports the guide means 43 and the die means, which will be described subsequently, and the lower end portion of plate 64 is attached to the base 21 by a plurality of bolts 65. Each member 60 has a compression spring 66 which acts between its outer surface 67 and a member 68 attached to the slide assembly 61 so that the member 60 and its associated toothed wheel 56 are yieldingly urged toward axis 62 holding a leading end portion of the convoluted strip 30 clamped against the spindle 36 during rotation thereof to enable pulling of the strip through the apparatus and helical winding of such strip.

In this example each shaft 57 is a driven shaft which is suitably mechanically connected to the motor 37 so that it rotates its wheel 56 in a synchronized manner with the spindle 36 and with the teeth 70 of each wheel 56 engaging a leading end portion of the strip 30 as it is wound and becomes a part of the tubing 42. However, it will be appreciated that the shafts 57 need not necessarily be driven and with shafts of this latter type each associated wheel 56 is still used as holding means yieldingly holding the leading end portion of the strip 30 against the spindle through the action of its compression spring 66.

The apparatus 20 comprises die means in the form of a plurality of successive forming dies 71 and 72 having stationary forming surfaces 73 and 74 y respectively, see FIGS. and 9. Each die 71 and 72 is attached to an associated die holder 75 which has a shaft portion 76 which is slidable within a collar 77 fixed to a support 80 which is in turn attached to the vertical plate 64 by a plurality of threaded bolts 81. A set screw 82 extends through a threaded opening in the collar 77 and engages the shaft 76 so that the position of the shaft and its associated forming die, either 71 or 72, may be adjusted toward and away from the central axis 62 of the spindle 36.

As seen particularly in FIGS. 5 and 6 of the drawings, the die 71 has a die passage 83 which is defined by stationary forming surfaces 73 and passage 83 extends the entire length of the die 71. The die passage 83 has a roughly rectangular configuration 83A at its inlet end and a roughly L-shaped configuration 83B at its outlet end. The stationary forming surfaces 73 cooperate to gradually change the straight cross-sectional configuration of the seam 44, as shown at 86 in FIG. 7, as it enters the inlet to a roughly L-shaped configuration as shown at 87 in FIG. 8.

The forming die 72 has a die passage 90 defined by stationary forming surfaces 74 and passage 90 extends the entire length of the die 72. The die passage 90 has a roughly L- shaped configuration 90A at its inlet end and a roughly bifolded or inverted U-shaped configuration 90B at its outlet end. Thus, upon passing an interlocked seam having the L- shaped configuration illustrated at 87 in FIG. 8 through the die 72 the stationary forming surfaces 74 gradually and smoothly change the Lshaped configuration to a bifolded or substantially inverted U-shaped configuration as illustrated at 92 in FIG. 11 and such bifolded seam is designated by the reference numeral 93.

The apparatus also has roller means in the form of a knurled roller 94, see FIGS. 3 and 13, which engages the interlocked, and now bifolded, seam following changing of its configuration by the successive dies 71 and 72 to flatten the seam toward the outside surface of the flexible tubing 42. The roller 94 is rotatably supported by a holder 95 which has a shaft portion 96. The shaft portion 96 extends within a collar 77 which is fixed to another support 80 which is also attached to the vertical plate64 by threaded bolts 81. A set screw 82 is provided for fixing the position of the shaft portion 96 and hence roller 94 in a precise manner with respect to the rotatable spindle 36.

The roller 94 engages the double thickness seam 93 and bends it from the dotted line position illustrated at 97 in FIG. 12 to the solid line position illustrated at 98 thereby partially flattening the double thickness seam toward the outside surface of the flexible tubing 42. As shown in FIG. 13, further flattening of the seam may be provided by the action of the first toothed wheel 56 that the flattened seam encounters whereby such seam is flattened from the dotted line position illustrated at 99 to the solid line position illustrated at 100. Still further flattening of the double thickness flattened seam may be provided by the action of the lowermost toothed wheel 56 as viewed in FIG. 3. However, it will be appreciated that such lowermost wheel need not necessarily be provided in certain applications of this invention.

Thus, it is seen that each toothed wheel 56 serves as a holding means for holding the leading end portion of the strip 30 against the spindle 36 while simultaneously providing flatten ing of the double thickness seam 93 against the outside surface of the tubing 42. In addition, the knurled roller 94 also serves as holding means holding the leading end portion of the strip 30 against the spindle 36.

As previously mentioned, the apparatus 20 has guide means 43 for guiding the U-shaped portion 31 so that it envelops the flange 33 to define the seam 44 and such guide means is illustrated in more detail in FIGS. 14-16 of the drawings and comprises a part of the fixture 63. The guide means 43 comprises a pair of guide members 101 and 102 which are detachably fastened to plate 64 in spaced parallel relation and outwardly of a surface 103 of the plate. The member 101 has a portion 104 which extends within and guides the U-shaped portion 31 so that it envelops flange 33, see FIG. 4, and member 102 has a portion 105 which engages and guides the flange 33 to assure that it is maintained substantially parallel to the U-shaped portion 31 while keeping flange 33 in an upright manner.

The member 101 is attached by bolts 107 to a block which is pivotally supported for movement in a horizontal plane on a horizontal leg portion of an L-shaped bracket 106 and bracket 106 is attached to the plate 64 by bolts 110. In a similar manner, the member 102 is attached to the plate 64 by a threaded bolt 111 and member 102 is precisely spaced from the plate 64 by a washer 112.

The members 101 and 102 have arcuate inner edges 113 and 114 respectively which correspond to the circumference of the particular flexible tubing 42 being made by the apparatus 20. In addition, the guide means 43 comprises a tubular member 115 which is fixed to the plate 64 in a cantilevered manner so that the spindle 36 extends therethrough and is freely rotatable. The member 115 has an outer edge 116 which serves as a stop and guide for the inner edge of the convoluted strip 30 to assure that the proper helix angle is maintained as the strip 30 is wound in a helical pattern to define the tubing 42.

The apparatus and method of this invention may be used to make flexible tubing ranging in diameter or size from 1% inches to 16 inches, and even larger. The fixture 63 is preferably provided as an assembly with its guide means such as members 101, 102, and 116 previously attached for a particular size tubing.

Each fixture 63 also has its plate 64 provided with suitable openings and guide surfaces to enable quick mounting of such plate on the base 21. In addition, the plate has suitable threaded openings therein for mounting the supports 80 for the dies 71 and 72 and the roller 94 in the manner previously explained. Thus, once it is desired to make flexible tubing of a given size a fixture for such size is quickly installed on the apparatus and such fixture will have the necessary guide means provided as a part thereof. The fixed forming dies and knurled roller 94 are then rapidly installed using the threaded openings in the plate 64. Because the toothed wheels 56 are carried by slide members 56 which are urged toward axis 62 of the spindle 36 by springs 66, such wheels will be automatically moved into their holding and flattening positions.

It will also be appreciated that the spindle 36 is also readily detachable and a different diameter spindle is provided for each different diameter of flexible tubing.

The web 23 may be of any suitable material, such as a metallic material, and the apparatus 20 has been successfully used in forming flexible tubing from cold rolled steel having a thickness generally of the order of 0.003 inch and 3003 aluminum alloy having a thickness generally of the order of 0.006 inch. However, it is to be understood that strip materials of various thicknesses may be wound into flexible tubes using the teachings of this invention.

The apparatus 20 is easy to operate even by an unskilled operator. The convoluted strip 30 exciting the convoluting assembly 22 is fed manually through the successive forming dies 71 and 72 and past roller 94 whereupon it is fed between the toothed wheels 56 and the spindle 36. The spindle 36 and wheels 56 are then started and with the continued operation of the assembly 22 the apparatus 20 operates to wind the strip in a helical pattern while interlocking side portions of such strip together merely by pulling such side portions through dies 71 and 72 having fixed forming surfaces and beneath flattening roller means to define the tubing 42.

While a present exemplary embodiment of this invention, and method of practicing the same, have been illustrated and described, it will be recognized that this invention may be otherwise variously embodied and practiced within the scope of the following claims. I

lclaim:

1. An apparatus for continuously making flexible tubing from a continuous strip of material having a roughly U-shaped portion along one side edge thereof and having a flange along on opposite side edge, said apparatus comprising, a base, a rotatable support supported for rotation on said base, means holding a leading end portion of said strip against said rotatable support during rotation thereof enabling helical winding of said strip into a plurality of adjacent turns to define said tubing, means guiding said U-shaped portion so that it envelops said flange to define a seam, and die means having a plurality of stationary forming surfaces which engage and change the cross-sectional configuration of said seam first from straight to generally L-shaped and then from generally L-shaped to bifolded, thereby interlocking said U-shaped portion and flange together.

2. An apparatus as set forth in claim 1 in which said guiding means comprises a pair of guide members with one of said members having a portion extending within and guiding said U-shaped portion and the other of said members having a portion engaging and guiding said flange.

3. An apparatus as set forth in claim 1 and further comprising a fixture which includes a plate fixed on said base, said guiding means comprising a pair of guide members detachably fastened to said plate in spaced parallel relation and outwardly of a surface thereof, one of said members having a portion extending within and guiding said U-shaped portion and the other of said members having a portion engaging and guiding said flange.

4. An apparatus as set forth in claim 3 and further comprising means for adjustably mounting said die means on said late. p 5. An apparatus for making flexible tubing from a continuous strip of material having a roughly U-shaped portion along one side edge thereof and having a flange along an opposite side edge, said apparatus comprising: a base, a rotatable support supported for rotation on said base, means holding a leading end portion of said strip against said rotatable support during rotation thereof enabling helical winding of said strip into a plurality of adjacent turns to define said tubing, means guiding said U-shaped portion so that it envelops said flange to define a seam, and die means including a plurality of successive forming dies each having stationary forming surfaces which engage and change the cross-sectional configuration of said seam to interlock said U-shaped portion and flange together.

6. An apparatus as set forth in claim 1 and further comprising roller means for engaging said seam following changing of its configuration by said die means to flatten said seam toward the outside surface of said tubing.

7. An apparatus as set forth in claim 1 in which said die means comprises a plurality of successive forming dies each having associated forming surfaces including a first die which has first forming surfaces which cooperate to change the cross-sectional configuration of said seam from straight to roughly L-shaped and a second forming die having second forming surfaces which cooperate to change said configuration from roughly L-shaped to bifolded.

8. An apparatus as set forth in claim 7 in which said first forming surfaces define a first die passage extending the entire length of said first die, said first die passage having a rectangular cross-sectional configuration at one end and an L-shaped configuration at its other end, said first forming surfaces providing a smooth gradual transition in the configuration of said first die passage between said rectangular and L-shaped configurations, and said second forming surfaces define a second die passage extending the entire length of said second die, said second die passage having an L-shaped configuration at one end and a U-shaped configuration at its other end, said second forming surfaces providing a smooth gradual transition in the configuration of said second die passage between said L-shaped and U-shaped configurations.

9. An apparatus as set forth in claim 1 and further comprising a convoluting assembly supported on said base, said convoluting assembly having a plurality of sets of cooperating rollers which engage a flat web of material and define said continuous strip having said U-shaped portion along one side edge and said flange along the opposite side edge.

10. An apparatus as set forth in claim 1 and further Comprising a cutting device and means supporting said device to enable cutting said tubing to desired lengths during the making thereof.

11. An apparatus as set forth in claim 1 in which said holding means comprises at least one wheel which engages said seam following changing of its configuration by said die means to flatten said seam toward the outside surface of said tubing.

12. An apparatus as set forth in claim 6 in which said holding means comprises a toothed wheel which is arranged after said roller means, said toothed wheel engaging said seam and clamping portions of said strip adjoining said seam against said rotatable support to thereby flatten said seam tightly against the outside surface of said tubing. 1

13. An apparatus as set forth in claim 1 in which said guiding means comprises a tubular member supported in a cantilevered manner around said rotatable support while allowing unobstructed rotation of said rotatable support, said tubular member having a terminal edge which serves as a stop and guide and assures that the proper helix angle is maintained during helical winding of said strip.

14. An apparatus as set forth in claim 13 in which said rotatable support comprises a rotatable spindle and further comprising a drive motor for rotating said spindle.

15. A method of making flexible tubing comprising the steps of, providing a continuous strip of material having a roughly U-shaped portion along one side edge thereof and having a flange along an opposite side edge, fixing a plurality of successive forming dies in spaced relation from a rotatable support, each of said dies having stationary forming surfaces, holding a leading end portion of said strip against said rotatable support, rotating said rotatable support with said leading end portion held thereagainst to helically wind said strip into a plurality of adjacent turns to define said tubing, and guiding said strip ahead of said dies so that said U-shaped portion envelops said flange to define a seam, said seam being pulled through said dies during said rotating step causing said stationary forming surfaces to engage and change the crosssectional configuration of said seam to interlock said U-shaped portion and said flange together.

16. A method as set forth in claim comprising the further step of engaging said seam with roller means following changing of its configuration by said die means to flatten said seam toward the outside surface of said tubing.

17. A method as set forth in claim 15 in which said providing step comprises the step of pulling a flat web through a convoluting assembly to define said continuous strip having said U-shaped portion along one side edge and said flange along the opposite side edge.

18. A method as set forth in claim 15 and comprising the further step of cutting a section of said flexible tubing simultaneously with the making of said tubing.

19. A method as set forth in claim 15 in which said guiding step comprises guiding one edge of said strip against a tubular guide member which is supported in a fixed position concentrically around said rotatable support, said tubular member having a terminal edge which serves as a stop and guide and assures that the proper helix angle is maintained as the strip is wound in a helical pattern during said rotating step.

20. Apparatus for making flexible tubing from a continuous strip of material having preshaped side edges adapted to interlock and form a seam, comprising a base, support means rotatably mounted on said base, means holding said strip against said support means during rotation thereof enabling helical winding of said strip into a plurality of adjacent turns to define said tubing, guide means fixed on said base against relative axial movement with respect to said rotatable support means for guiding said side edges of said strip into operative association to define a seam, and die means mounted adjacent said support means and having stationary forming surfaces which deform said side edges of said strip into interlocking engagement.

21. Apparatus as defined in claim 20, said die means being adjustably mounted relative to said support means.

22. Apparatus as defined in claim 20, said die means comprising a plurality of successive forming dies each having stationary forming surfaces.

23. Apparatus as defined in claim 22, wherein each of said dies is adjustably mounted relative to each support means.

24. Apparatus as defined in claim 20, comprising a mounting plate fixed to said base, said guide means including a pair of guide members detachably connected to said plate, one of said guide members guiding one side edge of said strip and the other of said guide members guiding the other side edge of said strip to form said seam, and said die means being mounted on said plate.

25. Apparatus as defined in claim 24, said die means comprising a plurality of successive forming dies adjustably mounted on said plate.

26. Apparatus as defined in claim 20, said rotatable support means rotating about an axis substantially perpendicular to the direction of feed of the continuous strip of material, and said guide means comprising a tubular member stationarily supported concentrically around said rotatable support means and including a terminal edge which serves as a stop and guide for a side edge of said strip and assures that the proper helix angle is maintained during helical winding of said strip around said support means.

27. A method of making flexible tubing comprising feeding a continuous strip of material to a tube forming station, opposite side portions of said strip being shaped so that they may be interlocked together, providing a support at said tube forming station which is rotatable about an axis generally perpendicular to the direction of feed of said strip, rotating said support while holding a leading end portion of said strip against said support to wind said strip into tubular form, fixing guide means adjacent said su ort and guiding said strip onto said support by way of said ixed guide means in a predetermined fashion so that said strip is helically wound around said support and said opposite side portions of said strip are engaged to define a seam, passing said seam through a plurality of stationary die forming surfaces located in spaced relation from said support to change the configuration of said seam and thereby interlock said opposite side portions of said strip together.

28. A method as defined in claim 27, comprising forming a generally U-shaped portion along one side of said strip and a flange portion along the other side of said strip prior to feeding said strip to said tube forming station, guiding said flange portions within said U-shaped portion to define said seam, and then bending said seam as it passes through said stationary die forming surfaces first to a generally L-shaped configuration and then to a bifolded configuration to interlock said U- shaped portion and flange portions together.

29. A method as defined in claim 28 comprising flattening said bifolded seam toward the outside surface of the formed tubing. 

1. An apparatus for continuously making flexible tubing from a continuous strip of material having a roughly U-shaped portion along one side edge thereof and having a flange along on opposite side edge, said apparatus comprising, a base, a rotatable support supported for rotation on said base, means holding a leading end portion of saId strip against said rotatable support during rotation thereof enabling helical winding of said strip into a plurality of adjacent turns to define said tubing, means guiding said U-shaped portion so that it envelops said flange to define a seam, and die means having a plurality of stationary forming surfaces which engage and change the cross-sectional configuration of said seam first from straight to generally Lshaped and then from generally L-shaped to bifolded, thereby interlocking said U-shaped portion and flange together.
 2. An apparatus as set forth in claim 1 in which said guiding means comprises a pair of guide members with one of said members having a portion extending within and guiding said U-shaped portion and the other of said members having a portion engaging and guiding said flange.
 3. An apparatus as set forth in claim 1 and further comprising a fixture which includes a plate fixed on said base, said guiding means comprising a pair of guide members detachably fastened to said plate in spaced parallel relation and outwardly of a surface thereof, one of said members having a portion extending within and guiding said U-shaped portion and the other of said members having a portion engaging and guiding said flange.
 4. An apparatus as set forth in claim 3 and further comprising means for adjustably mounting said die means on said plate.
 5. An apparatus for making flexible tubing from a continuous strip of material having a roughly U-shaped portion along one side edge thereof and having a flange along an opposite side edge, said apparatus comprising: a base, a rotatable support supported for rotation on said base, means holding a leading end portion of said strip against said rotatable support during rotation thereof enabling helical winding of said strip into a plurality of adjacent turns to define said tubing, means guiding said U-shaped portion so that it envelops said flange to define a seam, and die means including a plurality of successive forming dies each having stationary forming surfaces which engage and change the cross-sectional configuration of said seam to interlock said U-shaped portion and flange together.
 6. An apparatus as set forth in claim 1 and further comprising roller means for engaging said seam following changing of its configuration by said die means to flatten said seam toward the outside surface of said tubing.
 7. An apparatus as set forth in claim 1 in which said die means comprises a plurality of successive forming dies each having associated forming surfaces including a first die which has first forming surfaces which cooperate to change the cross-sectional configuration of said seam from straight to roughly L-shaped and a second forming die having second forming surfaces which cooperate to change said configuration from roughly L-shaped to bifolded.
 8. An apparatus as set forth in claim 7 in which said first forming surfaces define a first die passage extending the entire length of said first die, said first die passage having a rectangular cross-sectional configuration at one end and an L-shaped configuration at its other end, said first forming surfaces providing a smooth gradual transition in the configuration of said first die passage between said rectangular and L-shaped configurations, and said second forming surfaces define a second die passage extending the entire length of said second die, said second die passage having an L-shaped configuration at one end and a U-shaped configuration at its other end, said second forming surfaces providing a smooth gradual transition in the configuration of said second die passage between said L-shaped and U-shaped configurations.
 9. An apparatus as set forth in claim 1 and further comprising a convoluting assembly supported on said base, said convoluting assembly having a plurality of sets of cooperating rollers which engage a flat web of material and define said continuous strip having said U-shaped portion along one side edge and said Flange along the opposite side edge.
 10. An apparatus as set forth in claim 1 and further comprising a cutting device and means supporting said device to enable cutting said tubing to desired lengths during the making thereof.
 11. An apparatus as set forth in claim 1 in which said holding means comprises at least one wheel which engages said seam following changing of its configuration by said die means to flatten said seam toward the outside surface of said tubing.
 12. An apparatus as set forth in claim 6 in which said holding means comprises a toothed wheel which is arranged after said roller means, said toothed wheel engaging said seam and clamping portions of said strip adjoining said seam against said rotatable support to thereby flatten said seam tightly against the outside surface of said tubing.
 13. An apparatus as set forth in claim 1 in which said guiding means comprises a tubular member supported in a cantilevered manner around said rotatable support while allowing unobstructed rotation of said rotatable support, said tubular member having a terminal edge which serves as a stop and guide and assures that the proper helix angle is maintained during helical winding of said strip.
 14. An apparatus as set forth in claim 13 in which said rotatable support comprises a rotatable spindle and further comprising a drive motor for rotating said spindle.
 15. A method of making flexible tubing comprising the steps of, providing a continuous strip of material having a roughly U-shaped portion along one side edge thereof and having a flange along an opposite side edge, fixing a plurality of successive forming dies in spaced relation from a rotatable support, each of said dies having stationary forming surfaces, holding a leading end portion of said strip against said rotatable support, rotating said rotatable support with said leading end portion held thereagainst to helically wind said strip into a plurality of adjacent turns to define said tubing, and guiding said strip ahead of said dies so that said U-shaped portion envelops said flange to define a seam, said seam being pulled through said dies during said rotating step causing said stationary forming surfaces to engage and change the cross-sectional configuration of said seam to interlock said U-shaped portion and said flange together.
 16. A method as set forth in claim 15 comprising the further step of engaging said seam with roller means following changing of its configuration by said die means to flatten said seam toward the outside surface of said tubing.
 17. A method as set forth in claim 15 in which said providing step comprises the step of pulling a flat web through a convoluting assembly to define said continuous strip having said U-shaped portion along one side edge and said flange along the opposite side edge.
 18. A method as set forth in claim 15 and comprising the further step of cutting a section of said flexible tubing simultaneously with the making of said tubing.
 19. A method as set forth in claim 15 in which said guiding step comprises guiding one edge of said strip against a tubular guide member which is supported in a fixed position concentrically around said rotatable support, said tubular member having a terminal edge which serves as a stop and guide and assures that the proper helix angle is maintained as the strip is wound in a helical pattern during said rotating step.
 20. Apparatus for making flexible tubing from a continuous strip of material having preshaped side edges adapted to interlock and form a seam, comprising a base, support means rotatably mounted on said base, means holding said strip against said support means during rotation thereof enabling helical winding of said strip into a plurality of adjacent turns to define said tubing, guide means fixed on said base against relative axial movement with respect to said rotatable support means for guiding said side edges of said strip into operative association to define a seam, and die means mounted adjaCent said support means and having stationary forming surfaces which deform said side edges of said strip into interlocking engagement.
 21. Apparatus as defined in claim 20, said die means being adjustably mounted relative to said support means.
 22. Apparatus as defined in claim 20, said die means comprising a plurality of successive forming dies each having stationary forming surfaces.
 23. Apparatus as defined in claim 22, wherein each of said dies is adjustably mounted relative to each support means.
 24. Apparatus as defined in claim 20, comprising a mounting plate fixed to said base, said guide means including a pair of guide members detachably connected to said plate, one of said guide members guiding one side edge of said strip and the other of said guide members guiding the other side edge of said strip to form said seam, and said die means being mounted on said plate.
 25. Apparatus as defined in claim 24, said die means comprising a plurality of successive forming dies adjustably mounted on said plate.
 26. Apparatus as defined in claim 20, said rotatable support means rotating about an axis substantially perpendicular to the direction of feed of the continuous strip of material, and said guide means comprising a tubular member stationarily supported concentrically around said rotatable support means and including a terminal edge which serves as a stop and guide for a side edge of said strip and assures that the proper helix angle is maintained during helical winding of said strip around said support means.
 27. A method of making flexible tubing comprising feeding a continuous strip of material to a tube forming station, opposite side portions of said strip being shaped so that they may be interlocked together, providing a support at said tube forming station which is rotatable about an axis generally perpendicular to the direction of feed of said strip, rotating said support while holding a leading end portion of said strip against said support to wind said strip into tubular form, fixing guide means adjacent said support and guiding said strip onto said support by way of said fixed guide means in a predetermined fashion so that said strip is helically wound around said support and said opposite side portions of said strip are engaged to define a seam, passing said seam through a plurality of stationary die forming surfaces located in spaced relation from said support to change the configuration of said seam and thereby interlock said opposite side portions of said strip together.
 28. A method as defined in claim 27, comprising forming a generally U-shaped portion along one side of said strip and a flange portion along the other side of said strip prior to feeding said strip to said tube forming station, guiding said flange portions within said U-shaped portion to define said seam, and then bending said seam as it passes through said stationary die forming surfaces first to a generally L-shaped configuration and then to a bifolded configuration to interlock said U-shaped portion and flange portions together.
 29. A method as defined in claim 28 comprising flattening said bifolded seam toward the outside surface of the formed tubing. 